You have to know what computer programming is because only then, you will be able to understand why App inventor is way more easy than it.

What is purpose of a computer ?
Well, like any other machine computer has been created to perform specific tasks. Say for example a refrigerator in your home reduces the temperature to keep the food fresh.
Even though they seem to be same to some extent but, the tasks that a computer can perform is a way more superior and truly different from any other machine. Basically, they can perform operations like multiplication, addition or division e.t.c but, if you want to solve a more complex problem like calculating simple interest or compound interest then, you need to execute a program that can calculate it. But, before discussing more on programming you have to know what language does a computer understands.
What language does a computer understand?
Computers can understand only machine language. In machine language, each instruction is represented by a binary number. A binary number is a number that has only 1s and 0s. Ex: 110100. For me and you this may be just a number but, for computer it is an instruction and it is a command to perform some operation.
A computer program is a stream of binary numbers (representing instructions) which can be executed by the computer.
So, this rises a question that whether you have to learn machine language for programming? No, absolutely not necessary because of the availability of no of programming languages for different purposes. Ex: Java, c++ e.t.c
What does programming languages do?
Before writing any program the first step that every computer programmer does is
developing an algorithm. An algorithm is a set of logical steps that must be followed in order perform a specific task (as the steps we follow to find a solution for a mathematical problem). For example, if you were to create a program that can calculate an average for n numbers then, your algorithm would be like this
- Calculate sum of all the numbers
- Divide the sum with n (i.e, no of given numbers)
Algorithms are written in english and it is easy for me and you to understand it. but, in order to execute them on a computer we need to translate them into machine language. The process of translating an algorithm to machine language is very difficult and hence, we use Programming languages . Programming languages use words instead of numbers to represent instructions and it is the reason why they are easy to learn and understand. So, programmers use programming languages to write a program and this can be easily translated into machine language by special softwares called compilers or interpreters.
So, as you have understood why we need a programming language to perform a specific task on computer. Now, you can go further to learn about why App Inventor is easy than any programming language.